CNRFC - Hydrology - Observed River/Reservoir Conditions

MERCED RIVER - YOSEMITE NP AT HAPPY ISLES (HPIC1)

Latitude: 37.73º N	Longitude: 119.56º W	Elevation: 4017 Feet
Location: Mariposa County in California		River Group: San Joaquin

Monitor Stage: N/A

Flood Stage: 7.5 Feet

Observed Data Credit
	Raw streamflow data is provided by the US Geological Survey (USGS). View USGS Data for this station location.

Historical Stage/Flow Data
Note: Water Year 2025 is currently showing peak daily mean values. These will be updated to instantaneous peaks in the coming months.
Water Year	Peak Discharge (cfs)	Stage (feet)	Date
Most Recent 5 Years
2025	2,100	5.89	May 11, 2025
2024	2,980	6.80	May 19, 2024
2023	4,980	8.42	May 23, 2023
2022	2,430	6.25	Oct 25, 2021
2021	1,410	5.02	May 7, 2021
Historical High Stage/Flow Events (Period of Record - Aug 1915 to Present) - Ranked by Flow
1997	10,100	13.27	Jan 2, 1997
1956	9,840	12.73	Dec 23, 1955
1951	9,260	11.55	Nov 18, 1950
1965	9,240	11.50	Dec 23, 1964
1938	8,400	10.40	Dec 11, 1937
2018	8,060	10.09	Dec 07, 2018

Location Photographs
Upstream Photo	Gage House Photo	Downstream Photo

ESRI™ Locator Map

Official 7 Day National Weather Service Forecast (CAZ324)

Today: Slight chance of rain early in the morning, then rain in the late morning and afternoon. Highs 49 to 55. Northeast winds up to 5 mph shifting to the northwest in the afternoon. Chance of rain near 100 percent.

Tonight: Rain. Lows 38 to 46. Northwest winds up to 5 mph shifting to the northeast after midnight. Chance of rain near 100 percent.

New Years Day: Rain. Highs 46 to 52. South winds up to 10 mph. Chance of rain near 100 percent.

Thursday Night: Colder. Mostly cloudy in the evening then becoming partly cloudy. Lows 32 to 40. Southeast winds up to 10 mph.

Friday: Partly sunny. Highs 47 to 55. Southeast winds up to 10 mph.

Friday Night: Mostly cloudy. Chance of rain in the evening, then rain after midnight. Lows 35 to 43. Chance of rain 80 percent.

Saturday: Rain in the morning, then rain showers and chance of thunderstorms in the afternoon. Highs 43 to 49. Chance of precipitation near 100 percent.

Saturday Night: Rain showers. Light snow accumulations. Near steady temperature in the lower 40s. Chance of showers 90 percent.

Sunday and Sunday Night: Rain showers and snow showers. Moderate snow accumulations. Highs 40 to 48. Lows 31 to 39. Chance of precipitation 90 percent.

Monday: Rain showers and snow showers likely in the morning, then rain showers and snow showers in the afternoon. Moderate snow accumulations. Highs 38 to 46. Chance of precipitation 80 percent.

Monday Night: Mostly cloudy. Rain showers likely in the evening, then chance of rain and snow after midnight. Lows 30 to 38. Chance of precipitation 70 percent.

Tuesday: Partly sunny with a 50 percent chance of rain and snow. Highs 41 to 49.

Flood Impacts
13.27 Feet	Flood of Record: 1/2/97. $178 million in damage to Yosemite Valley.
10.0 Feet	Northside Drive at Wosky Pond, Southside Drive at Chapel Meadow, El Capitan crossover, and Sentinel crossover are impassable to vehicles.
8.2 Feet	Swinging Bridge overtops. Water on road at Northside Drive, Southsie Drive, El Capitan crossover, and Sentinel crossover.
7.5 Feet	Flood Stage. Housekeeping camp and Yosemite Valley backpacker campground begin to flood.
7.0 Feet	North Pines and Lower Pines campgrounds begin flooding.

Product Disclaimer

This river graphic is not intended to serve as a substitute for official flood watches, warnings, advisories, or statements issued by the NWS San Joaquin Valley-Hanford Weather Forecast Office. Observations are preliminary and subject to change. River levels identified as "forecast" should be consistent with those contained in official NWS products. River levels identified as "guidance" have significant uncertainty due to future weather or reservoir regulation and are provided for planning purposes only.

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